Intrauterine contraceptive device

ABSTRACT

An integral intrauterine contraceptive device comprises a relatively thick elongated stem, a downwardly bowed crossbar secured to the top of the stem, and a pair of downwardly and inwardly extending arms formed as continuations of the crossbar. The crossbar and arm construction is designed for atraumatic embedding in the endometrium to reduce expulsion caused by uterine contractions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to contraceptive devices and particularly tointrauterine contraceptive devices.

2. Description of the Prior Art

U.S. Pat. No. 3,533,406 discloses an intrauterine contraceptive devicehaving a "T" shape. The device is completely placed into the endometrialcavity where the end of the stem extends toward the cervical os when thecross bar of the "T" lies at the fundus of the uterus. The contraceptiveefficacy of the "T" device has proven unacceptable for many families. Asa result, the "T" device has been used in many applications as a carrierfor contraceptive chemicals such as copper. It is believed that therelatively small cross section of the stem of the "T" device prevents itfrom having the desired contraceptive effect. The so-called "7" shapeddevices have produced effects nearly identical to the "T" devices. Boththe "T" and "7" devices are lightweight and embed somewhat in theendometrial tissue. Expulsion rates and bleeding are modest, primarilybecause of the form and size of the devices.

U.S. Pat. No. 3,881,475 discloses an intrauterine contraceptive devicehaving a pair of loops extending in opposite directions from a commonstem. Each loop has a free end. This design has attempted to provide adevice wherein the loops are capable of more readily conforming to thewalls of the uterine cavity and are soft enough to move with the uterinewalls as they move or contract. Higher expulsion rates and removal ratesare reported with use of the device.

U.S. Pat. No. 3,937,217 provides an intrauterine contraceptive devicewhich resembles the "T" device but which has a loop formed in the end ofthe stem and has a less rigid crossbar construction. This patenteddevice has as its primary object the reduction of bleeding, involuntaryexpulsion and occasional perforation into the cervix associated with the"T" device. Other intrauterine contraceptive devices having similarconstructions are described in U.S. Pat. Nos. 3,454,004; 3,457,915;3,810,456 and 3,842,826.

Thus, it becomes an object of the present invention to provide anintrauterine contraceptive device having the advantages associated withthe above-described devices, but with increased contraceptive efficacy,lower expulsion rates and less bleeding and pain for the patient.

SUMMARY OF THE INVENTION

The present invention provides an intrauterine contraceptive devicehaving a relatively thick stem, a downwardly bowed crossbar secured tothe top of the stem and a pair of downwardly and inwardly extending armsformed as continuations of the cross bar with the free ends of the armsterminating as enlarged fin-like portions. The crossbar and stem areadapted to lie in the fold between the anterior and posterior walls ofthe endometrium with the upper portion of the stem being of around-ended rectangular, elliptical-like cross section with the plane ofthe long axis thereof being perpendicular to the crossbar and providinga stem thickness of 4 mm to 6 mm between such walls. The shape andresilience of the crossbar and arms serve to propel the device towardthe fundus during uterine contractions thereby reducing the chance ofexpulsion. The simple design makes possible a lightweight device whichresults in reduced bleeding and pain for the patient. The mentioned 4 mmto 6 mm dimension represents a preferred thickness for the desiredresults.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of the intrauterine contraceptive device ofthe present invention.

FIG. 2 is a side elevation view of the device.

FIG. 3 is an end elevation view of the device.

FIG. 4 is a bottom plan view of the device.

FIG. 5 is an enlarged section view taken substantially along line 5--5of FIG. 2.

FIG. 6 is an enlarged, fragmentary section view taken substantiallyalong line 6--6 of FIG. 2.

FIG. 7 is an enlarged section view taken substantially along line 7--7of FIG. 2.

FIG. 8 is an enlarged section view taken substantially along line 8--8of FIG. 4.

FIG. 9 is a side elevation view of an alternative embodiment of theinvention device.

FIG. 10 is an enlarged section view taken substantially along line10--10 of FIG. 9.

FIG. 11 is an enlarged section view taken substantially along line11--11 of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, the intrauterine contraceptive device 10 ofthe present invention includes a relatively thick stem 11, a downwardlybowed crossbar 12 and a pair of inwardly extending arms 13, 14 formed ascontinuations of crossbar 12. Stem 11 is formed with an upper portion 17which is somewhat elliptical or of round-ended rectangular shape incross section. In the specific embodiment, the major or long axis X(FIG. 5) of this section .[.of.]. .Iadd.is .Iaddend.approximately 4 mmwith the minor axis Y (FIG. 5) being approximately 2 mm. A continuouscircular lip 18 is formed at the base of upper portion 17 to act as anabutment for an inserter tube (not shown). The lower end 19 of stem 11is circular in cross section and is smaller in cross sectional area thanthat of upper portion 17. Dimension X provides a desired thickness.

A pair of arms 13, 14 are formed as continuations of crossbar 12 andproject downwardly and inwardly toward stem 11 and terminate short oftouching the stem. The line of each of the arms 13, 14 defines anincluded angle of 50° with respect to the central axis of the stem, with40° to 70° being an acceptable range (see FIG. 2). Also, arms 13, 14 areangled 10° in opposite directions out of the central plane through thestem and cross bar (see FIGS. 1, 3 and 4) to allow the arms to crossover and slide by the lower end 19 of stem 11 during insertion.

For insertion, the lower end 19 of stem 11 slidably fits into the end ofan inserter tube. The curved leading portion 22 of device 10 is theninserted into the uterus, at which time crossbar 12 becomes bowedfurther downwardly and arms 13, 14 cross over stem 11. The device isfully inserted when the crossbar lies adjacent the fundus of the uterus.It should be noted that the device may be constructed with the arms 13,14 in the same plane with stem 11 and crossbar 12 (i.e., without theabove-described 10° offsets). However, with such an alternativeconstruction, the arms 13, 14 do not automatically cross over stem 11and the inserter tube during insertion unless the physician firstrotates the arms out of the mentioned plane so that they will assume amomentary "fix" in an offset position and will retain such fix duringinsertion. This alternative construction has proven adequate but it doesrequire an added step to be performed by the physician.

The leading portion 22 of the device is tapered, as seen in FIG. 6, togently dilate the internal os during insertion. Once the device 10 isfully inserted, crossbar 12 and arms 13, 14 return to their normalpositions. A small hole 20 in end 19 receives a withdrawal thread 21useful for removal of the device in the manner well known to thoseskilled in the art.

As illustrated in FIGS. 7 and 8, crossbar 12 and arms 13, 14 havehalf-round cross sections which provide atraumatic embedding in theanterior and posterior walls of the endometrium. The unique shape ofdevice 10 allows the device to resist expulsion due to contractions ofthe uterus and thereby maintain a position at the fundus. Contractionsof the fundus of the uterus cause crossbar 12 to bow further and propelfurther towards the fundus. Contractions of the lower uterine segmentimpinge on arms 13, 14 and also serve to propel the device toward thefundus. A pair of flat fins 15, 16 are formed at the tips of arms 13, 14to reduce the possibility of the arms perforating the tissue duringcontractions of the uterus or during insertion and orient as shown.

The contraceptive efficacy of the device may be primarily attributed tothe thickness (approximately 5 mm) of the upper portion 17 of stem 11 asseen in cross section in FIG. 5. A thickness of 5 mm is preferred, with4.0 to 6.0 mm being an acceptable range. Although device 10 has agreater thickness at the critical point (i.e., upper stem portion 17),the overall mass of the device is substantially less than mostcontraceptive devices. This reduced mass is the primary reason for thelow levels of bleeding and pain associated with the device and thereduced tendency of the uterus to expel the device.

In the illustrated embodiment, shaft 11 has a length of approximately 20mm with end 19 being 8 mm in length and upper portion 17 being 12 mm.End 19 has an outside diameter of approximately 2 mm, which correspondswith the inside diameter of the inserted tube (not shown). Crossbar 12spans 30 mm (approximately the lateral dimension of the fundus) and hasa radius of curvature on the order of 30 mm. Crossbar 12 and arms 13, 14are half-round in cross section with an outwardcurved surface and aninward flat surface which has a width of approximately 2 mm. Fins 15, 16flatten out to approximately 3 mm in width. Since the entire device 10is not placed within an inserter tube, the device does not have to havea fully resilient "memory" for returning to its normal shape aftersubstantial periods of distortion. As explained above, during insertiononly the crossbar 12 and arms 13, 14 are distorted. These members easilyreturn to their normal positions when the device 10 is fully insertedand comes to rest between the anterior and posterior walls of theendometrium.

Referring now to FIGS. 9, 10 and 11, an alternative embodimentintrauterine contraceptive device 10' is illustrated as having a pair ofcrossbar extensions 30, 31 which extend beyond the intersection point ofarms 13', 14'. Extensions 30, 31 provide further atraumatic embedding inthe walls of the endometrium. Extensions 30, 31 further resist expulsiondue to contractions of the uterus and thereby maintains device 10' inposition at the fundus. Thus, where additional atraumatic embedding andexpulsion resistance is desired this alternative embodiment may beemployed.

From the foregoing description, it may be seen that the art is nowprovided with an intrauterine contraceptive device having (1) animproved contraceptive efficacy due in large part to the stem thicknesswhich is disposed between the anterior and posterior walls of theendometrium; (2) a very low expulsion rate deriving from the atraumaticembedding of the crossbar and arms in the endometrium and the tendencyof the crossbar and arms to propel the device toward the fundus duringuterine contractions; (3) a reduced tendency to cause bleeding and paindue to its low mass; and (4) a resilient construction allowing ease ofinsertion without the physician having to insert the entire device intoan inserter tube. Those skilled in the art will recognize that thepresent invention represents a substantial departure from the prior artand that the invention is not limited solely to the specific embodimentdescribed in detail.

The plastic material used to mold the described device as an integralstructure may be polyethelene, an ethylene-vinyl acetate (EVA) copolymeror any like material well known in the art.

What is claimed is:
 1. An intrauterine contraceptive devicecomprising:a. an elongated stem having an upper portion and a lowerportion.[.;.]..Iadd., said stem upper portion having a thickness ofbetween 4.0 to 6.0 mm as measured in a plane perpendicular to theanterior and posterior walls of the endometrium when the device isinserted in the uterus; .Iaddend. b. a resilient downwardly bowedcrossbar integrally secured at its midpoint to the tip of said stemupper portion; and c. a pair of resilient arms formed as integralcontinuations of the opposed ends of said crossbar, said arms beingangled downwardly and inwardly toward said stem and terminating short oftouching said stem, and the line of each of said arms defining anincluded angle with the central axis of said stem of between 40° and70°. .[.2. A device as claimed in claim 1 wherein said stem upper endhas a thickness of between 4.0 to 6.0 mm as measured in a planeperpendicular to said crossbar to provide such thickness in a planeperpendicular to the anterior and posterior walls of the endometriumwhen the device is inserted in the uterus..].
 3. A device as claimed inclaim .[.2.]. .Iadd.1 .Iaddend.wherein said thickness is 4 mm.
 4. Adevice as claimed in claim 1 wherein said included angle is on the orderof 50°.
 5. A device as claimed in claim 1 wherein said arms include flatfin portions at their ends oriented to reduce tissue penetration of saidarms during use of said device.
 6. A device as claimed in claim 1wherein said arms are angled in opposite directions out of the centralplane through the stem and crossbar adapting said arms to cross over andslide by said stem during insertion of the device.
 7. A device asclaimed in claim 6 wherein each said arm is angled out of said plane byan angle on the order of 10°.
 8. A device as claimed in claim 7including a pair of crossbar extensions forming a continuation of saidcrossbar beyond the point of intersection of said arms and said crossbarand adapted to provide additional embedding of said device during usethereof.
 9. A device as claimed in claim 1 wherein said stem is on theorder of 20 mm in length and said crossbar spans a distance on the orderof 30 mm and has a radius of curvature on the order of 30 mm.
 0. Anintrauterine contraceptive device adapted to lie in the fold between theanterior and posterior walls of the endometrium comprising:a. anelongated stem having a lower portion and an upper portion, said upperportion having a thickness between 4.0 to 6.0 mm in a directionperpendicular to the anterior and posterior walls of the endometriumwith said device installed therebetween and said lower portion having anoutside diameter adapted for being slidably received by an insertertube; b. a resilient downwardly bowed crossbar integrally secured at itsmidpoint to the tip of said stem upper portion; and c. a pair ofresilient arms formed as integral continuations of the opposed ends ofsaid crossbar, said arms being angled downwardly and inwardly towardsaid stem and terminating short of touching said stem, and the line ofeach of said arms defining an included angle with the central axis ofsaid stem of between 40° and 70°, said arms having flat fin-likeportions at the ends thereof oriented to reduce tissue penetrationduring use thereof, and said arms being angled in opposite directionsout of the central plane through the stem and crossbar.
 11. A device asclaimed in claim 10 wherein said upper stem portion thickness is 4 mm.12. A device as claimed in claim 11 wherein said included angle is onthe order of 50°.
 13. A device as claimed in claim 12 wherein each saidarm is angled out of said plane by an angle on the order of 10°.
 14. Adevice as claimed in claim 13 wherein said stem is on the order of 20 mmin length and said crossbar spans a distance on the order of 30 mm andhas a radius of curvature on the order of 30 mm. .Iadd.
 15. Anintrauterine contraceptive device comprising:(a) an elongated stemhaving an upper portion and a lower portion, said stem upper portionbeing of non-circular cross section and having a thickness of between4.0 to 6.0 mm as measured in a plane perpendicular to the anterior andposterior walls of the endometrium when the device is inserted in theuterus between said walls; and (b) a foldable, flexible arm structuredepending from said upper portion of said stem and formed in a shape toprovide atraumatic embedding in the anterior and posterior walls of theendometrium and to resist expulsion during contraction of the fundus..Iaddend.